Question

Go through following matches with respect to biocontrol agents, and select the correct option.
A. Ladybird beetle – Aphids
B. Dragonflies – Mosquitoes
C. Bacillus thuringiensis – Butterflies/caterpillars
D. Trichoderma – Plant pathogens

• A. Only (A) and (B) are correct.
• B. Only (C) is correct.
• C. Only (D) is correct.
• D. All (A), (B), (C), and (D) are correct.

Answer 1

Answer: (D)

Biocontrol agents prevent the plant against pests and disease.
Ladybird beetle is a biocontrol agent which protects the plant from aphids. Aphids are small fly-like plant pests which attack both ornamental plants and garden crops.
Dragonflies are natural predators which are effective against mosquitoes. They eat hundreds of mosquitoes each day. Thus, they are used to control the population of mosquitoes.
Bacillus thuringiensis (Bt) is a microbial biocontrol agent that can be introduced to control butterfly caterpillars. These are available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as Brassica species and fruit trees, where these are eaten by insect larvae. In the gut of the larvae, the toxin is released and the larvae get killed. The bacterial disease kills the caterpillars, but leave other insects unharmed.
Trichoderma is a biological control being developed for use in the treatment of plant diseases. They are free-living fungi that are very common in the root ecosystems and are effective against several plants pathogens.